This research is motivated by the importance of water for human, animals and plants. Humans need water for various needs such as drinking, cooking, cleaning themselves and cleaning equipment. The use of water for basic needs must fulfill various water quality parameters. Water quality parameters include pH, turbidity, metal content and so on. One of the water quality parameters is pH. To find out pH Value it can use pH meter. In previous study a pH meter was made with the Arduino UNO microcontroller with accuracy of the device was 94.7%, while in this research was made pH meter with NodeMCU microcontroller which id connected to WiFi and application on smartphone Based on the results of the product analysis, this product has an accuracy value of 98.68%, this value is higher than previous studies, even higher than PH-009(I)A. While the error value of this product is only 1.32%, this value is also better than PH-009(I)A and from previous research products. While the precision of this tool is expressed in the RSD value. The smaller RSD value indicates that the tool has a better precision. RSD's value of the product is 0.32%, while the PH-009(I)A is 2.52%.